Which API Protocols and Definition Formats Does SoapUI Support?
SoapUI supports REST, SOAP, and GraphQL APIs, with the site also listing Apache Kafka and gRPC under its multi-protocol support. On the definition side, it lists WSDL, OpenAPI, AsyncAPI, Apache Avro, Swagger, and Protobuf. One important caveat: the site presents these capabilities across its product line, and the exact protocol and definition coverage can differ between the open-source SoapUI and the commercial ReadyAPI, so confirm the specific edition before committing.
Protocols SoapUI Covers
According to the SoapUI site, multi-protocol support includes:
| Protocol | Typical use |
|---|---|
| REST | HTTP-based web APIs |
| SOAP | XML-based web services |
| GraphQL | Query-language APIs |
| Apache Kafka | Event streaming / messaging |
| gRPC | High-performance RPC services |
If your testing needs are limited to REST and SOAP fundamentals, the open-source SoapUI is positioned as the entry point. If you need the broader protocol set alongside advanced testing types, the site points to ReadyAPI.
Definition Formats SoapUI Can Work With
The site lists these definition and schema formats:
- WSDL — for SOAP services
- OpenAPI — for REST API descriptions
- Swagger — the earlier name/format family for REST descriptions
- AsyncAPI — for asynchronous and event-driven APIs
- Apache Avro — schema format often used with Kafka
- Protobuf — interface definition for gRPC
This matters because importing a definition is usually how you bootstrap a test project: you supply the service definition, and the tool generates the request structure you then assert against.
Open Source vs. ReadyAPI: Where the Coverage Differs
The site's comparison table separates the two editions, and the split is not just about protocol count:
| Capability | ReadyAPI | SoapUI Open Source |
|---|---|---|
| Multi-protocol support | REST, SOAP, GraphQL, Apache Kafka, gRPC | Listed as available |
| Automation | Property transfer, custom scripting, CI/CD integrations, data generation, dynamic data sources, assertion groups | Basic |
| Collaboration | Jira, Slack, GitHub, Bitbucket, GitLab | — |
| Definitions | WSDL, OpenAPI, AsyncAPI, Apache Avro, Swagger, Protobuf | — |
| Testing | Functional, security, performance, service virtualization & mocking | Basic functional and basic performance testing |
The practical reading: the open-source edition gets you started with fundamentals, while security testing, load testing, and service virtualization sit on the ReadyAPI side. The table does not spell out per-protocol availability for each edition, so treat the protocol list as product-line coverage rather than a guarantee for the free download.
How to Decide
- Testing REST or SOAP APIs with basic functional checks → start with SoapUI Open Source.
- Working with GraphQL, Kafka, or gRPC → verify the specific edition supports your protocol before building a workflow around it.
- Needing security, performance, or mocking/virtualization → the site places these under ReadyAPI.
- Importing a definition (WSDL, OpenAPI, etc.) → confirm your edition accepts that format, since the comparison table does not break this down per edition.
The site also offers a 30-minute on-demand webinar aimed at teams trying to align API quality across QA, Dev, and DevOps, which is worth watching if the edition choice is a team decision rather than an individual one.